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  • Forbush decreases and turbulence levels at coronal mass ejection fronts 
    SUBRAMANIAN, PRASAD; Antia, H.M.; Dugad, S. R.; Goswami, U.D.; Gupta, S. K.; Hayashi, Y.; Ito, N.; Kawakami, S.; Kojima, H.; Mohanty, P.K.; Nayak, P.K.; Nonaka, T.; Oshima, A.; Sivaprasad, K.; Tanaka, H.; Tonwar, S.C. (EDP Sciences, 2009-02)
    Aims. We seek to estimate the average level of MHD turbulence near coronal mass ejection (CME) fronts as they propagate from the Sun to the Earth. Methods. We examined the cosmic ray data from the GRAPES-3 tracking muon ...
  • Driving currents for fluxrope coronal mass ejection 
    SUBRAMANIAN, PRASAD; Vourlidas, Angelos (American Astronomical Society, 2009-03)
    We present a method for measuring electrical currents enclosed by flux rope structures that are ejected within solar coronal mass ejections (CMEs). Such currents are responsible for providing the Lorentz self-force that ...
  • Proposed visible emission line space solar coronagraph 
    SUBRAMANIAN, PRASAD; Singh Jagdev et al. (Indian Academy of Sciences, 2011-01)
    The outer atmosphere of the sun called the corona has been observed during total solar eclipse for short periods (typically < 6 min), from as early as the eighteenth century. In the recent past, space-based instruments ...
  • Constraints on coronal turbulence models from source sizes of noise storms at 327 MHz 
    SUBRAMANIAN, PRASAD; Cairns, Iver (American Geophysical Union, 2011-03)
    [1] We seek to reconcile observations of small source sizes in the solar corona at 327 MHz with predictions of scattering models that incorporate refractive index effects, inner scale effects, and a spherically diverging ...
  • Velocity profile of interplanetary coronal mass ejections beyond 1 AU 
    Lara, A.; Flandes, A.; Borgazzi, A.; SUBRAMANIAN, PRASAD (Wiley, 2011-12)
    [1] We analyze the dynamics of interplanetary coronal mass ejections (ICMEs) through the interplanetary medium from the lower solar corona to ∼5.3 AU. Our analysis uses a one‐dimensional hydrodynamical model derived from ...
  • TeV blazar variability: the firehose instability? 
    SUBRAMANIAN, PRASAD; Shukla, Amit; Becker, Peter A. (Oxford University Press, 2012-06)
    Recently observed minute-time-scale variability of blazar emission at TeV energies has imposed severe constraints on jet models and TeV emission mechanisms. We focus on a robust jet instability to explain this variability. ...
  • Can solar wind viscous drag account for coronal mass ejection deceleration? 
    SUBRAMANIAN, PRASAD; Lara, Alejandro; Borgazzi, Andrea (American Geophysical Union, 2012-10)
    [1] The forces acting on solar Coronal Mass Ejections (CMEs) in the interplanetary medium have been evaluated so far in terms of an empirical drag coefficient CD ∼ 1 that quantifies the role of the aerodynamic drag experienced ...
  • High-rigidity Forbush decreases: due to CMEs or shocks? 
    Arunbabu, K. P.; Antia, H.M.; Dugad, S. R.; Gupta, S. K.; Hayashi, Y.; Kawakami, S.; Mohanty, P.K.; Nonaka, T.; Oshima, A.; SUBRAMANIAN, PRASAD (EDP Sciences, 2013-07)
    Aims. We seek to identify the primary agents causing Forbush decreases (FDs) in high-rigidity cosmic rays observed from the Earth. In particular, we ask if these FDs are caused mainly by coronal mass ejections (CMEs) from ...
  • Self-similar Expansion of solar coronal mass ejections: Implications for Lorentz self-force driving 
    SUBRAMANIAN, PRASAD; Arunbabu, K. P.; Vourlidas, Angelos; Mauriya, Adwiteey (IOP Publishing, 2014-07)
    We examine the propagation of several coronal mass ejections (CMEs) with well-observed flux rope signatures in the field of view of the SECCHI coronagraphs on board the STEREO satellites using the graduated cylindrical ...
  • A study of density modulation index in the inner heliospheric solar wind during solar cycle 23 
    Bisoi, Susanta Kumar; Janardhan, P.; INGALE, MADHUSUDAN; SUBRAMANIAN, PRASAD; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K. (IOP Publishing, 2014-10)
    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, epsilon N ≡ ΔN/N) is of vital importance for understanding several problems in heliospheric physics ...
  • Coronal turbulence and the angular broadening of radio sources – the role of the structure function 
    INGALE, MADHUSUDAN; SUBRAMANIAN, PRASAD; Cairns, Iver (Oxford University Press, 2015-03)
    The amplitude of density turbulence in the extended solar corona, especially near the dissipation scale, impinges on several problems of current interest. Radio sources observed through the turbulent solar wind are broadened ...
  • The structure of solar radio noise storms 
    Mercier, C.; SUBRAMANIAN, PRASAD; Chambe, G.; Janardhan, P. (EDP Sciences, 2015-04)
    Context. The Nançay Radioheliograph (NRH) routinely produces snapshot images of the full sun (field of view ~3 R⊙) at 6 or 10 frequencies between 150 and 450 MHz, with typical resolution 3 arcmin and time cadence 0.2 s. ...
  • How are Forbush decreases related to interplanetary magnetic field enhancements 
    Arunbabu, K. P.; Antia, H.M.; Dugad, S. R.; Gupta, S. K.; Hayashi, Y.; Kawakami, S.; Mohanty, P.K.; Oshima, A.; SUBRAMANIAN, PRASAD (EDP Sciences, 2015-07)
    Aims. A Forbush decrease (FD) is a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity. We seek to understand the relationship between the FDs and near-Earth interplanetary ...
  • CME propagation: where does aerodynamic drag "take over"? 
    Sachdeva, Nishtha; SUBRAMANIAN, PRASAD; Colaninno, Robin; Vourlidas, Angelos (IOP Publishing, 2015-08)
    We investigate the Sun–Earth dynamics of a set of eight well observed solar coronal mass ejections (CMEs) using data from the Solar Terrestrial Relations Observatory spacecraft. We seek to quantify the extent to which ...
  • Relative contribution of the magnetic field barrier and solar wind speed in icme-associated forbush decreases 
    Bhaskar, Ankush; SUBRAMANIAN, PRASAD; Vichare, Geeta (IOP Publishing, 2016-09)
    We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997–2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought ...
  • Transient Weakening of Earth’s Magnetic Shield Probed by a Cosmic Ray Burst 
    SUBRAMANIAN, PRASAD; Mohanty, P.K. et al. (American Physical Society, 2016-11)
    The GRAPES-3 tracking muon telescope in Ooty, India measures muon intensity at high cutoff rigidities (15–24 GV) along nine independent directions covering 2.3 sr. The arrival of a coronal mass ejection on 22 June 2015 ...
  • Amplitude of solar wind density turbulence from 10 to 45 R⊙ 
    Raja, K. Sasikumar; INGALE, MADHUSUDAN; Ramesh, V; SUBRAMANIAN, PRASAD; Manoharan, P. K.; Janardhan, P. (American Geophysical Union, 2016-12)
    We report on the amplitude of the density turbulence spectrum ( urn:x-wiley:jgra:media:jgra53108:jgra53108-math-0001) and the density modulation index (δN/N) in the solar wind between 10 and 45R⊙. We derive these quantities ...
  • CME Dynamics Using STEREO and LASCO Observations: The Relative Importance of Lorentz Forces and Solar Wind Drag 
    Sachdeva, Nishtha; SUBRAMANIAN, PRASAD; Vourlidas, Angelos; Bothmer, Volker (Springer Nature, 2017-09)
    We seek to quantify the relative contributions of Lorentz forces and aerodynamic drag on the propagation of solar coronal mass ejections (CMEs). We use Graduated Cylindrical Shell (GCS) model fits to a representative set ...
  • Small electron acceleration episodes in the solar corona 
    James, Tomin; SUBRAMANIAN, PRASAD; Kontar, Eduard P. (Oxford University Press, 2017-10)
    We study the energetics of non-thermal electrons produced in small acceleration episodes in the solar corona. We carried out an extensive survey spanning 2004–2015 and shortlisted six impulsive electron events detected at ...
  • Turbulent Density Fluctuations and Proton Heating Rate in the Solar Wind from 9–20 R ⊙ 
    Raja, K. Sasikumar; SUBRAMANIAN, PRASAD; Ramesh, R.; Vourlidas, Angelos; INGALE, MADHUSUDAN (IOP Publishing, 2017-11)
    We obtain scatter-broadened images of the Crab Nebula at 80 MHz as it transits through the inner solar wind in 2017 and 2016 June. These images are anisotropic, with the major axis oriented perpendicular to the radially ...

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